I’ve Level 31 with The Lost Vikings, and they are my second most played hero in Hero/Storm League over the history of the game (this is my external data, dunno about my internal stats with them).
Multi-unit control heroes have always kinda been my thing since I come from a background of playing many RTS games like Starcraft.
In regards to my take on them, I believe that over time the Vikings have become fairly problematic in how much they warp games that they’re in to generally be much less fun for everyone else involved. It’s a complicated problem to solve that would likely require big changes to how they work if we wanted to live in a world where it’s ok for them to be seen as much as more standard heroes like Valla or Li-Ming.